This invention relates to four point or quad type seals.
In a four point or quad seal, the seal has a generally rectangular configuration and defines annular sealing surfaces at each of its four corners.
In a typical application, the pair of concentric annular sealing surfaces at one annular side face of the seal typically constitute a pressure seal to maintain a pressure condition in the associated piston and cylinder assembly and the two concentric sealing surfaces at the other annular side face of the seal function to keep contaminates out of the sealing interface.
Seals of this general type are especially effective in piston and cylinder environments where the first set of sealing surfaces acts to maintain the pressure in the pressure chamber of the piston cylinder and the second set of sealing surfaces preserves the sealing effectiveness Of the first set Of sealing surfaces by preventing the entry of contaminates into the sealing environment. However, seals of this type include a relatively large volume of rubber and this large volume of rubber detracts from the travel efficiency and the load efficiency of the associated piston and cylinder assembly Specifically, the axial compression or squishing occurring in the large rubber volume of the four point type seal increases the lost motion or travel of the associated cylinder assembly with a consequent derogation in the travel efficiency of the cylinder assembly. Further, the squishing of the rubber generates high friction losses which derogate the load efficiency of the cylinder assembly in the sense of reducing the load output of the assembly as compared to the load input.